Well, you're voluntarily changing your destination which is precisely the definition of ICAO for in-flight replanning. Whereas when you go to your alternate after having been unsuccessful you're forced to go to your alternate. Imagine there is literally no way you can land at your destination and you know this well in advance. So you decide to go to your alternate. Distance to your second alternate ( if needed when you initially planned) renders it impossible to make it there, which is precisely what we were discussing airborne the other day. Now, by choosing this "declared" alternate, are you commiting to land?